Research

Light InSight Series Schedule

Lectures and Abstracts

All lectures take place on Tuesdays from 5:00 pm - 6:00 pm and are free and open to the public. Because of limited seating availability, please RSVP on a link below. For more information, contact IYL2015@neco.edu.

March 24, 2015: “Functional Imaging of Single Cells in the Living Eye”

Abstract: The correction of the eye’s aberrations with adaptive optics (AO) has made it possible to image the normal and diseased retina of the living eye at microscopic resolution. I will describe recent developments in the deployment of this technology, many of which combine AO and other imaging modalities with the goal of obtaining not only structural but also functional information at a cellular and sometimes subcellular spatial scale. I will illustrate the value of this approach with examples including single and two-photon fluorescence imaging of individual retinal cells, which allows us to optically probe the electrical signals the retina sends to the brain as well as molecular events in photoreceptors that would otherwise be invisible. It may be that these high resolution imaging tools, combined with recent advances in our ability to record from and control neurons with light, will eventually help complete our understanding of the computations the retina performs that allow us to see, and also help to restore vision in the blind.

March 31, 2015: “Color: Neuroscience and Art Practice”

Abstract: What is color for and how do we see it? Color is a fundamental determinant of visual experience, yet we know scandalously little about its role in behavior and how it is computed by the brain. I am interested in addressing these questions using traditional neuroscience techniques in addition to multidisciplinary studies of art history and art practice. Paintings are the product of our brain’s neural machinery, which has been sculpted during evolution, and modified by cultural exposure and development. By examining artists’ painting practices, my goal is to discover hints to how the brain works, gain insight into the impact of artists on culture, and inform my ongoing scientific studies of the brain’s mechanisms for encoding and decoding color.

April 7, 2015: “Intrinsically Photosensitive Retinal Ganglion Cells”

David Berson, Dept. of Neuroscience, Brown University

Abstract: A small subset of retinal ganglion cells exhibit robust light responses even when all influences from classical photoreceptors (rods and cones) are eliminated. These intrinsically sensitive retinal ganglion cells (ipRGCs) use a novel photopigment called melanopsin to generate their intrinsic light responses. Though discovered in rodents, ipRGCs are present in humans and, apparently, all other vertebrates. These neurons are essential for a variety of reflexive or homeostatic responses to environmental illumination, including photic synchronization of circadian rhythms, constriction of the pupil and neuroendocrine responses, photic pain, and modulation of sleep and mood. These findings help to explain why many physiological responses to light responses persist in mammals, including humans, with retinal blindness resulting from loss of rods and cones. We are pursuing many new lines of inquiry about these cells, including their unexpected diversity (comprising at least six types), their diverse functional roles in visually driven behavior, and their surprising ability to distribute their output signals within the retina itself. These ‘centrifugal’ signals appear to activity-dependent development of the visual system and retinal adaptation to environmental light.

April 14, 2015: “Light and Circadian Rhythms”

Charles Czeisler, Harvard Medical School, Harvard University

May 26, 2015: “Light in Architecture”

Zenovia Toloudi, Arts & Sciences, Dartmouth College

June 23, 2015: “Light and Development of Refractive Error”

Frances Rucker, New England College of Optometry

Abstract: At birth most, but not all eyes, are too small, they are hyperopic. Over the course of the first few years of life the eye grows, becoming emmetropic, through a process called emmetropization. In some cases, emmetropization fails, the eye grows too much, and the eye becomes myopic. The eye is able to guide the emmetropization process by using visual cues, but the brain’s interpretation of these cues is affected by several factors in the visual environment. For example, visual environments that are deficient in blue light (as with some indoor illuminants) or activities that affect the rate of visual stimulation (reading, video games) will change the way that the emmetropization mechanism functions and drive the refraction away from emmetropia. This talk will review recent research on the visual cues for emmetropization and explore the question of how the eye knows when it is defocused and why some eyes may develop myopia under certain visual conditions.

July 21, 2015: “Understanding and Improving Vision Through New Optical Technologies”

Susana Marcos, Instituto de Optica, Madrid, Spain

Abstract: Quantitative knowledge of the structure, morphology and optical quality of the eye’s optics is possible through new optical imaging-based technologies. These techniques have developed into diagnostic tools of clinical use. Optics is also a key technology for developing new optical correction designs. Furthermore, the impact of changes in the optics of the eye (through aging, pathology or treatment) as well as the effect of neural adaptation can be explored using novel optical technologies (such as adaptive optics). This talk will present how these technologies hold promise in improving visual treatments, by incorporating new paradigms considering accurate ocular biometry and neural adaptation.

August 25, 2015: “Light and Lighting”

Mark Rea, Lighting Research Center, Rensselaer Polytechnic Institute

Abstract: The definition of light and application of light (i.e., lighting) should be distinct. The candela is the fundamental unit in the Standard International (SI) system for quantifying light, but unlike all other fundamental units (e.g., the second or the meter) it can have multiple definitions, depending upon the luminous efficiency function selected to weight the electromagnetic spectrum. For consistency with other fundamental units the candela should be based upon a single spectral weighting function that represents the human eye sensitivity to optical radiation. Therefore, a universal luminous efficiency function characterizing the spectral sensitivity of all neural channels emanating from the retina should be formally adopted into the SI system. In contrast, lighting should vary depending upon the visual channel important for the application. Thus, there should be a set of benefit luminous efficiency functions to choose from for different lighting applications. The selection would depend upon the neural channel deemed most important for that application. Where, for example, reading text is the most important function in the application, the well established photopic luminous efficiency function, V(l), would be selected to compare the effectiveness of different light sources. For safe navigation in an otherwise dark movie theater, the scotopic luminous efficiency function, V’(l), would be selected. For driving where off-axis detection of objects moving onto the highway (e.g., deer) is most important the spectral power distribution of street lights should be weighted in terms of a mesopic luminous efficiency function. Even non-visual channels should be part of the family of benefit luminous efficiency functions. Where regulating the circadian rhythms of submariners is important, the spectral sensitivity of the human circadian system should be used for light source selection. Following these recommendations would make the candela like all other fundamental units in the SI system and, more importantly for society, would maximize the benefits lighting provides people while minimizing wasted electric energy.

September 8, 2015: “Light as a Potential Treatment for Myopia in Children”

Abstract: Research shows that myopic children and those who later become myopic spend fewer hours in outdoor activity than their non-myopic counterparts. It appears that the relevant factor is the light intensity found outdoors rather than the activity. A related finding is that the progression of myopia in the summer, when children are more likely to be outdoors in sunlight, is half that found during the winter. Results from animal models show that high intensity light slows eye growth and the development of myopia. All these results, taken together, suggest that light may be useful as a treatment for myopia. A small clinical trial reported slowed progression of myopia in children randomized to more vs. less time outdoors. The mechanism whereby light slows eye growth is not known, but may involve dopamine, vitamin D, and/or pupillary constriction with an increased depth of focus. If future studies show that exposure to high light intensity or particular wavelengths of light slows the progression of myopia in children, this could be a simple, cost-effective method of treating myopia.

September 15, 2015: “Probing RPE with Light”

Abstract: Lipofuscin accumulates throughout life in the RPE as a byproduct of the visual cycle and is a complex mixture of bisretinoids (including A2E) and their oxidized forms. Mutations in photoreceptor genes can have a direct impact on RPE lipofuscin levels, such as is the case for ABCA4-related retinal disorders. Adverse effects of RPE lipofuscin has been demonstrated in-vitro including generation of free radicals and photooxidation-associated complement activation. We have developed different in-vivo methods to quantify the autofluorescence of lipofuscin. These techniques will aid in achieving a better understanding of the role of lipofuscin in disease pathogenesis, and could contribute to the assessment of drug and gene therapies.

September 22, 2015: Optogenetics in Retinal Degenerative Diseases

Abstract: Retinal ganglion cells, the final output neurons of the retina, are a target for strategies aimed at restoring vision after retinal degeneration. Most retinal degenerations affect primarily the photoreceptor cells; the ganglion cells survive. If they could be effectively activated by light, some level of vision might be restored. The anatomy and function of retinal ganglion cells will be reviewed: they come in roughly 30 different types, each sending a different coding of the visual stimulus to the brain. Experiments in mice show proof of principle that an animal with degenerated photoreceptors can be granted simple vision when gene therapy methods are used to express light sensitive proteins in the retinal ganglion cells. Some of the issues in advancing this strategy to the clinic will be discussed.

October 6, 2015: “Circadian Rhythms and Emmetropization”

Abstract: All circadian rhythms are entrained by the cycle of light and dark, so that light at crucial times phase-shifts rhythms to a precise 24-hour period. Light can also have “acute” effects, such as melatonin release, that are also phase-dependent. “Circadian disruption” is defined as a perturbation of the endogenous circadian rhythmicity, and includes both phase and amplitude characteristics of biological processes that exhibit an endogenous, 24 hour rhythm, and encompasses such disturbances as phase shifts and/or the acute effects on an “output” of the clock. In chickens, monkeys, and humans, eyes elongate more during the day than at night, in approximate anti-phase to a rhythm in choroidal thickness. Circadian disruptions in these diurnal rhythms are strongly associated with alterations in ocular growth patterns and refractive development in chicks and monkeys: their phases and/or amplitudes are altered in eyes growing too fast, in response to form deprivation (no image) or minus lens-induced hyperopic defocus, or too slowly, in response to plus lens-induced myopic defocus. This presentation will describe how “time of day” (phase) is crucial in determining the growth responses of eyes to various visual stimuli such as retinal defocus, or normal “in focus” vision at night. I will show that stimuli that cause eye growth stimulation at certain times of day are associated with disruptions in the rhythms in eye length and choroid thickness, while those that do not alter growth are not. Finally, I will present preliminary data showing that the effects of the growth-inhibiting drugs atropine and dopamine agonists are more effective when given at one time than another, arguing that anti-myopia therapies in children should consider time of day as a variable

October 27, 2015: “Art, Aging and the Visual System”

John Werner, Ophthalmology & Vision Science, University of California, Davis

Abstract: Substantial age-related change occurs in the optics of the human eye and in retinal neural pathways. It is often expected that color perception will be altered in the elderly due to brunescence of the aging lens. This expectation is sensible, but wrong. We shall illustrate this through one of the most celebrated case studies purported to show the opposite, the cataract of the French Impressionist, Claude Monet. His paintings and recent laboratory results demonstrate that the visual system continuously renormalizes itself to maintain stabile perception throughout the life span.